#' Make a select rows node.
#'
#' @param source source to select from.
#' @param expr expression to select rows.
#' @param env environment to look for values in.
#' @return select columns node.
#'
#' @examples
#'
#' my_db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
#' d <- dbi_copy_to(my_db, 'd',
#' data.frame(AUC = 0.6, R2 = 0.2))
#' eqn <- select_rows_se(d, "AUC >= 0.5")
#' cat(format(eqn))
#' sql <- to_sql(eqn, my_db)
#' cat(sql)
#' DBI::dbGetQuery(my_db, sql)
#' DBI::dbDisconnect(my_db)
#'
#' @export
#'
select_rows_se <- function(source, expr,
env = parent.frame()) {
have <- column_names(source)
vnam <- setdiff(paste("rquery_select_condition", 1:(length(have)+1), sep = "_"),
have)[[1]]
parsed <- parse_se(source, vnam := expr, env = env)
assignments <- unpack_assignments(source, parsed)
parsed[[1]]$symbols_produced <- character(0)
r <- list(source = list(source),
table_name = NULL,
parsed = parsed,
expr = assignments)
r <- relop_decorate("relop_select_rows", r)
r
}
#' Make a select rows node.
#'
#' @param source source to select from.
#' @param expr expression to select rows.
#' @param env environment to look for values in.
#' @return select columns node.
#'
#' @examples
#'
#' my_db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
#' d <- dbi_copy_to(my_db, 'd',
#' data.frame(AUC = 0.6, R2 = 0.2, z = 3))
#' eqn <- select_rows_nse(d, AUC >= 0.5) %.>%
#' select_columns(., "R2")
#' cat(format(eqn))
#' sql <- to_sql(eqn, my_db)
#' cat(sql)
#' DBI::dbGetQuery(my_db, sql)
#' DBI::dbDisconnect(my_db)
#'
#' @export
#'
select_rows_nse <- function(source, expr,
env = parent.frame()) {
have <- column_names(source)
vnam <- setdiff(paste("rquery_select_condition", 1:(length(have)+1), sep = "_"),
have)[[1]]
exprq <- substitute(expr)
parsed <- parse_nse(source, list(exprq), env = env)
parsed[[1]]$symbols_produced <- vnam
assignments <- unpack_assignments(source, parsed)
parsed[[1]]$symbols_produced <- character(0)
r <- list(source = list(source),
parsed = parsed,
expr = assignments)
r <- relop_decorate("relop_select_rows", r)
r
}
#' @export
format.relop_select_rows <- function(x, ...) {
if(length(list(...))>0) {
stop("unexpected arguemnts")
}
paste0(trimws(format(x$source[[1]]), which="right"),
" %.>%\n ",
"select_rows(., ", x$parsed[[1]]$presentation, ")",
"\n")
}
calc_used_relop_select_rows <- function (x, ...,
using = NULL,
contract = FALSE) {
if(length(using)<=0) {
using <- column_names(x)
}
consuming <- merge_fld(x$parsed, "symbols_used")
using <- unique(c(using, consuming))
missing <- setdiff(using, column_names(x$source[[1]]))
if(length(missing)>0) {
stop(paste("rquery::calc_used_relop_select_rows unknown columns",
paste(missing, collapse = ", ")))
}
using
}
#' @export
columns_used.relop_select_rows <- function (x, ...,
using = NULL,
contract = FALSE) {
cols <- calc_used_relop_select_rows(x,
using = using,
contract = contract)
return(columns_used(x$source[[1]],
using = cols,
contract = contract))
}
#' @export
to_sql.relop_select_rows <- function (x,
db,
...,
source_limit = NULL,
indent_level = 0,
tnum = mkTempNameGenerator('tsql'),
append_cr = TRUE,
using = NULL) {
if(length(list(...))>0) {
stop("unexpected arguemnts")
}
# re-quote expr
re_quoted <- redo_parse_quoting(x$parsed, db)
re_expr <- unpack_assignments(x$source[[1]], re_quoted,
check_is_assignment = FALSE)
# work on query
cols <- calc_used_relop_select_rows(x,
using = using)
subsql <- to_sql(x$source[[1]],
db = db,
source_limit = source_limit,
indent_level = indent_level + 1,
tnum = tnum,
append_cr = FALSE,
using = cols)
tab <- tnum()
prefix <- paste(rep(' ', indent_level), collapse = '')
q <- paste0(prefix, "SELECT * FROM (\n",
subsql, "\n",
prefix, ") ",
tab, "\n",
prefix, "WHERE ",
re_expr)
if(append_cr) {
q <- paste0(q, "\n")
}
q
}
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